Magnitude 6.7 Earthquake Jolts India, Bangladesh: AIR Worldwide

A magnitude 6.7 earthquake hit northeast India near its border with Myanmar and Bangladesh on Jan. 4 at 4:35 a.m. local time, about 29 kilometers (18 miles) northwest of Imphal, the capital of Manipur state, according to catastrophe modeling firm AIR Worldwide.

The quake, which reportedly lasted as long as 60 seconds, occurred while many people were asleep. The current casualty toll of nine deaths is expected to rise, with rescue efforts hampered by severed power supplies and telecommunication links, said the report from AIR and other news reports. (The population of Imphal is approximately 270,000).

The India Meteorological Department placed the epicenter of the quake in the Tamenglong region of Manipur state, at a depth of about 17 kilometers (about 10 miles); the U.S. Geological Survey (USGS) reported the depth at 55 kilometers (about 34 miles), AIR said in a statement.

“In addition to all the northeastern states, tremors also were felt in Bihar, Jharkhand, and West Bengal, including Kolkata, the capital of West Bengal state,” said Dr. Bingming Shen-Tu, assistant vice president and senior principal scientist at AIR Worldwide.

“The USGS posted user-submitted reports of moderate-to-strong ground shaking from many locations in the far eastern part of India, too, as well as west of the epicenter in neighboring Bangladesh. Lighter ground shaking was reported over a wide region as far as 1,000 kilometers (620 miles) from the epicenter. Shaking affected large parts of Bhutan, Myanmar, and Nepal, countries that also border India,” Shen-Tu said.

An M3.6 aftershock occurred about 9:27 a.m., local time, followed by an M3.4 aftershock at about 2:30 p.m.

According to the National Disaster Management Authority (NDMA), damage to a few buildings, residential units, and government offices have been reported, including damage to a newly constructed six-story building in Imphal. Power to Imphal City has been disrupted, and some power installations have suffered damage, AIR said in its report.

Other damage in Imphal includes collapsed roofs and staircases and the walls of some school buildings. Reportedly some roadways and at least 30 buildings have developed cracks, including in a market complex.

The Nagaland State Disaster Management Agency said that strong tremors were felt across the state, but there were no reports of any damage. The official residence of the Additional Deputy Commissioner of Cachar district, which is near the epicenter at Tamenglong in Manipur, was damaged, as was the fire station building in Cachar, AIR continued.

According to the USGS, the earthquake occurred as a result of predominantly strike-slip faulting in the complex plate boundary region between the Indian and Eurasian plates in Southeast Asia. “In the region of the earthquake, the Indian plate is moving toward the north-northeast with respect to the Eurasian plate at a velocity of approximately 48 millimeters (1.9 inches) per year,” AIR reported.

Earthquake Prone Region

Moderate-to-large earthquakes in this region are fairly common, AIR said, noting that during the preceding century, 19 other M6-plus earthquakes have occurred within 250 kilometers (155 miles) of the 2016 event. The largest, an M8.0 earthquake in 1946, struck 220 kilometers (137 miles) to the southeast of the 2016 earthquake on the Sagaing Fault, AIR said.

Other nearby damaging events include an M7.3 earthquake 150 kilometers (93 miles) to the east of the 2016 event in August 1988, which caused several fatalities and dozens of injuries, and a M6.0 earthquake 90 km (56 miles) to the southwest in December 1984 which caused 20 fatalities and 100 injuries, AIR continued in its report.

“Northeast India has seen some of the biggest quakes in history, such as the 1897 M8.0 Shillong quake. In 1950, an M8.6 earthquake in Assam forced the mighty Brahmaputra River to change its course. In September 2011, Sikkim suffered heavy damage after being hit by an M6.9 quake,” Shen-Tu noted.